A hiker walking at a constant rate of 4 miles per hour is passed by a cyclist traveling in the same direction along the same path at a constant rate of 20 miles per hour. The cyclist stops to wait for the hiker 5 minutes after passing her, while the hiker continues to walk at her constant rate. How many minutes must the cyclist wait until the hiker catches up?
20min。Below is the reasoning: in the 5minutes, the distance passed by the hiker is 1/3 mile, that passed by the cyclist being 5/3 mile. Thus, the distance between the hiker and the cyclist is 4/3 mile. It takes 20 minutes for the hiker to walk that far (4/3divided by 4 and multiplied by 60 minutes). Therefore, the answer is 20 minutes
20min。Below is the reasoning: in the 5minutes, the distance passed by the hiker is 1/3 mile, that passed by the cyclist being 5/3 mile. Thus, the distance between the hiker and the cyclist is 4/3 mile. It takes 20 minutes for the hiker to walk that far (4/3divided by 4 and multiplied by 60 minutes). Therefore, the answer is 20 minutes
-- by 会员 Rainbeauty (2011/6/7 15:12:24)
谢谢你！没做对的原因在于题没看懂，那句wait for the hiker 5minutes after passing her，我以为是pass后立即等5分钟。。原来是继续走5分钟后再等。。！
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发表于 2011-6-7 14:42:03
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